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Surface deposition based on metal-phenolic networks (MPNs) has received increasing interest in recent years. The catechol structure is generally considered to be essential to the formation of MPNs. Our most recent results have demonstrated that some kinds of monophenols can form MPNs on substrate surfaces. Herein, we report a fast and effective surface-coating system based on the coordination of 3-(4-hydroxy-3-methoxyphenyl)-2-propenoic acid, a kind of monophenol, with Fe3+. Compared with other metal ions such as Cu2+ and Ni2+, Fe3+ with stronger electron acceptability can coordinate with the monophenol more strongly to form MPNs, and moreover, the deposition time significantly decreases to 40 min from generally 24 h. It is demonstrated that the deposition process is controlled by the coordination, Fe3+ hydrolysis, and deprotonation of the monophenol. The coatings endow substrates such as polypropylene microfiltration membrane with underwater superoleophobicity, which can be applied in oil/water separation with high separation efficiency and great long-term stability. In addition, the coated membranes are positively charged and thus are useful in selective adsorption of dyes. The present work not only provides a novel, fast, and one-step deposition method to fabricate MPNs, but also demonstrates that the fabrication efficiency of monophenol-based MPNs is comparable with that of polyphenol-based MPNs.

The lithium (Li) metal polymer battery (LMPB) is a promising candidate for solid-state batteries with high safety. However, high voltage stability of such a battery has been hindered by the use of polyethylene oxide (PEO), which oxidizes at a potential lower than 4 V versus Li. Herein, we adopt the polymer-in-salt electrolyte (PISE) strategy to circumvent the disadvantage of the PEO-lithium bis(fluorosulfonyl)imide (LiFSI) system with EO/Li ≤ 8 through a dry ball-milling process to avoid the contamination of the residual solvent. The obtained solid-state PISEs exhibit distinctly different morphologies and coordination structures which lead to significant improvement in oxidative stability. P(EO)1LiFSI has a low melting temperature, a high ionic conductivity at 60 °C, and an oxidative stability of ∼4.5 V versus Li/Li+. With an effective interphase rich in inorganic species and a good stability of the hybrid polymer electrolyte toward Li metal, the LMPB constructed with Li||LiNi1/3Co1/3Mn1/3O2 can retain 74.4% of capacity after 186 cycles at 60 °C under the cutoff charge voltage of 4.3 V. The findings offer a promising pathway toward high-voltage stable polymer electrolytes for high-energy-density and safe LMPBs.

Surface vacancies, serving as the activation centers for surface-adsorbed species, have been widely applied in catalysts to improve their activity and selectivity. In the case of ternary compound semiconductors, there is some controversy about exposed atoms and surface defects. Two-dimensional layered BiOCl is an important photocatalyst, which has had numerous studies focused on its oxygen vacancy (OV) and bismuth vacancy (BiV). It has been realized that its (001) surface can consist of exposed halogen atoms rather than oxygen atoms, which thus needs a new explanation for its surface defect engineering mechanism. Using first-principles calculations, the activation behavior of NOX (NO2, NO, N2O) at a chlorine vacancy (ClV) on the BiOCl (001) surface is systematically studied. It is found that after introducing ClV on BiOCl (001) surfaces, NOX molecules all show excellent activities with longer chemical bonds by capturing electrons from the catalyst. Our work furnishes fundamental insight into the activation of small molecules on defect-rich surfaces of ternary compound catalysts.

A novel electrolyte system with an excellent low-temperature performance for lithium-ion batteries (LIBs) has been developed and studied. It was discovered for the first time, in this work, that when isoxazole (IZ) was used as the main solvent, the ionic conductivity of the electrolyte for LIBs is more than doubled in a temperature range between -20 and 20 °C compared to the baseline electrolyte using ethylene carbonate-ethyl methyl carbonate as solvents. To solve the problem of solvent co-intercalation into the graphite anode and/or electrolyte decomposition, the lithium difluoro(oxalato)borate (LiDFOB) salt and fluoroethylene carbonate (FEC) additive were used to form a stable solid electrolyte interphase on the surface of the graphite anode. Benefitting from the high ionic conductivity at low temperature, cells using a new electrolyte with 1 M LiDFOB in FEC/IZ (1:10, vol %) solvents demonstrated a very high reversible capacity of 187.5 mAh g-1 at -20 °C, while the baseline electrolyte only delivered a reversible capacity of 23.1 mAh g-1.

Metallic zinc is an ideal anode due to its high theoretical capacity (820 mAh g−1), low redox potential (−0.762 V versus the standard hydrogen electrode), high abundance and low toxicity. When used in aqueous electrolyte, it also brings intrinsic safety, but suffers from severe irreversibility. This is best exemplified by low coulombic efficiency, dendrite growth and water consumption. This is thought to be due to severe hydrogen evolution during zinc plating and stripping, hitherto making the in-situ formation of a solid–electrolyte interphase (SEI) impossible. Here, we report an aqueous zinc battery in which a dilute and acidic aqueous electrolyte with an alkylammonium salt additive assists the formation of a robust, Zn2+-conducting and waterproof SEI. The presence of this SEI enables excellent performance: dendrite-free zinc plating/stripping at 99.9% coulombic efficiency in a Ti||Zn asymmetric cell for 1,000 cycles; steady charge–discharge in a Zn||Zn symmetric cell for 6,000 cycles (6,000 h); and high energy densities (136 Wh kg−1 in a Zn||VOPO4 full battery with 88.7% retention for >6,000 cycles, 325 Wh kg−1 in a Zn||O2 full battery for >300 cycles and 218 Wh kg−1 in a Zn||MnO2 full battery with 88.5% retention for 1,000 cycles) using limited zinc. The SEI-forming electrolyte also allows the reversible operation of an anode-free pouch cell of Ti||ZnxVOPO4 at 100% depth of discharge for 100 cycles, thus establishing aqueous zinc batteries as viable cell systems for practical applications. A solid–electrolyte interphase that is permeable to Zn(ii) ions but waterproof is formed using an aqueous electrolyte composition. Cycling performances in an anode-free aqueous pouch cell show promise for intrinsically safe energy storage applications.

Aqueous zinc batteries dominate the primary battery market with alkaline chemistries and recently have been rejuvenated as rechargeable devices to compete for grid-scale energy storage applications. Tremendous effort has been made in the past few years and improved cyclability has been demonstrated in both alkaline, neutral, and mild acidic systems. In this review/perspective, we will elucidate the merits of rechargeable aqueous zinc batteries through side-by-side comparison to Li-ion batteries, examine the challenges and progress made in the pursuit of highly rechargeable alkaline and mild acidic batteries, and finally provide a holistic forward look at the technology. The focus is placed on static closed cell designs, while flow batteries and open systems like zinc-air batteries will not be included due to space constraint.

The lithium metal anode is considered as the ultimate choice for high-energy-density batteries. However, the organic-dominated solid electrolyte interphase (SEI) formed in carbonate electrolytes ha...

Electrospun nanofibrous membranes (ENM) possess many advantages over commonly utilized water purification systems. They provide high porosity with interconnected pores and a high surface to volume ratio, facilitating particle adsorption. Affinity separation moves into a promising future for application, for example, nanoparticle adsorption with excellent filtration efficiency, because of its highly specific adsorption mechanism. However, not all effects on filtration performance are entirely understood. In this paper, we investigate significant filtration parameters, such as pore size, mechanical stability, and hydrophilicity, and determine a sequence of importance for an optimal pressure drop. Copolymers with various hydrophilic functional groups such as acid, amide, pyridine, and quaternary amine were utilized. Effects on the pressure drop or nanoparticle filtration efficiency can then easily be attributed to the corresponding functional group. UV-light was used to induce cross-linking in the membranes, which subsequently surpassed the mechanical stability of commonly used hydrophobic membranes. A maximum tensile-stress of up to 11.6 MPa was obtained, whereby an optimization of at least 22% was achieved. Moreover, these cross-links reduce fiber swelling by a maximum of 26%. The membrane potential depends on the different functional groups and their incorporation number from 10 to 50 mol %. Successful gold nanoparticle (AuNP) filtration in flow mode was demonstrated and highlighted the outstanding membrane properties and selectivity. The Nplus membrane achieved 100% filtration efficiency over a duration of 6 min, surpassing the Pyr membrane's performance. This was attributed to the ionic interaction of the Nplus membrane, in contrast with the physical adsorption of the Pyr membrane.

Mussel-inspired surface modification has received significant interest in recent years because of its simplicity and versatility. The deposition systems are still mainly limited to molecules with catechol chemical structures. In this paper, we report a novel deposition system based on a monophenol, vanillic acid (4-hydroxy-3-methoxybenzoic acid), to fabricate metal-phenolic network coatings on various substrates. The results of the water contact angle and zeta potential reveal that the modified polypropylene microfiltration membrane is underwater superhydrophobic and positively charged, showing applications in oil/water separation and dye removal. Furthermore, the single-face modified Janus membrane is promising in switchable oil/water separation. The results demonstrate a novel example of the metal-monophenolic deposition system, which expands the toolbox of surface coatings and facilitates the understanding of the deposition of phenols.

The kinetics of aqueous outer-sphere electron-transfer (ET) reactions are determined in large part by noncovalent electrostatic interactions that originate from the surrounding electrolyte solution...

Electrochemical reduction of nitrogen to ammonia under mild conditions provides an intriguing approach for energy conversion. A grand challenge for electrochemical nitrogen reduction reaction (NRR) is to design a superior electrocatalyst to obtain high performance including high catalytic activity and selectivity. In the NRR process, the three most important steps are nitrogen adsorption, nitrogen activation, and ammonia desorption. We take MoS2 as the research object and obtain catalysts with different electronic densities of states through the doping of Fe and V, respectively. Using a combination of experiments and theoretical calculations, it is demonstrated that V-doped MoS2 (MoS2-V) shows better nitrogen adsorption and activation, while Fe-doped MoS2 (MoS2-Fe) obtains the highest ammonia yield in experiments (20.11 µg·h−1·mg−1cat.) due to its easier desorption of ammonia. Therefore, an appropriate balance between nitrogen adsorption, nitrogen activation, and ammonia desorption should be achieved to obtain highly efficient NRR electrocatalysts.

A comprehensive understanding of the solid–electrolyte interphase (SEI) composition is crucial to developing high-energy batteries based on lithium metal anodes. A particularly contentious issue concerns the presence of LiH in the SEI. Here we report on the use of synchrotron-based X-ray diffraction and pair distribution function analysis to identify and differentiate two elusive components, LiH and LiF, in the SEI of lithium metal anodes. LiH is identified as a component of the SEI in high abundance, and the possibility of its misidentification as LiF in the literature is discussed. LiF in the SEI is found to have different structural features from LiF in the bulk phase, including a larger lattice parameter and a smaller grain size (

Rechargeable zinc metal batteries (RZMBs) offer a compelling complement to existing lithium ion and emerging lithium metal batteries for meeting the increasing energy storage demands of the future. Multiple recent reports have suggested that optimized electrolytes resolve a century-old challenge for RZMBs by achieving extremely reversible zinc plating/stripping with Coulombic efficiencies (CEs) approaching 100%. However, the disparity among published testing methods and conditions severely convolutes electrolyte performance comparisons. The lack of rigorous and standardized protocols is rapidly becoming an impediment to ongoing research and commercialization thrusts. This Perspective examines recent efforts to improve the reversibility of the zinc metal anode in terms of key parameters, including CE protocols, plating morphology, dendrite formation and long-term stability. Then we suggest the most appropriate standard protocols for future CE determination. Finally, we envision future strategies to improve zinc/electrolyte stability so that research efforts can be better aligned towards realistic performance targets for RZMB commercialization. Zinc metal batteries (ZMBs) provide a promising alternative to lithium metal batteries but share the formidable challenges in reversibility. The authors discuss the key performance metrics of ZMBs and propose a protocol to assess the true reversibility of zinc metal anodes.

Hydrogenation is an effective approach to improve the performance of photocatalysts within defect engineering methods. The mechanism of hydrogenation and synergetic effects between hydrogen atoms and local electronic structures, however, remain unclear due to the limits of available photocatalytic systems and technical barriers to observation and measurement. Here, we utilize oxygen vacancies as residential sites to host hydrogen atoms in a layered bismuth oxychloride material containing defects. It is confirmed theoretically and experimentally that the hydrogen atoms interact with the vacancies and surrounding atoms, which promotes the separati30on and transfer processes of photo-generated carriers via the resulting band structure. The efficiency of catalytic activity and selectivity of defective bismuth oxychloride regarding nitric oxide oxidation has been improved. This work clearly reveals the role of hydrogen atoms in defective crystalline materials and provides a promising way to design catalytic materials with controllable defect engineering. Hydrogenated BiOCl shows high performance as a semiconductor photocatalyst, but the mechanism and synergetic effects of hydrogenation are hard to study. Here interactions of oxygen vacancies and hydrogen atoms in BiOCl nanosheets show a modulation of energy dispersion, which leads to both improvements in charge separation and photocatalytic activity.

The impact of thermal history on the kinetic response of thin thermoresponsive diblock copolymer poly(diethylene glycol monomethyl ether methacrylate)-block-poly(poly(ethylene glycol) methyl ether methacrylate), abbreviated as PMEO2MA-b-POEGMA300, films is investigated by in situ neutron reflectivity. The PMEO2MA and POEGMA300 blocks are both thermoresponsive polymers with a lower critical solution temperature. Their transition temperatures (TTs) are around 25 °C (TT1, PMEO2MA) and 60 °C (TT2, POEGMA300). Thus, by applying different temperature protocols (20 to 60 or 20 to 40 to 60 °C), the PMEO2MA-b-POEGMA300 thin films experience different thermal histories: the first protocol directly switches from a swollen to a collapsed state, whereas the second one switches first from a swollen to a semicollapsed and finally to a collapsed state. Although the applied thermal histories differ, the response and final state of the collapsed films are very close to each other. After the thermal stimulus, both films present a complicated response composed of an initial shrinkage, followed by a rearrangement. Interestingly, a subsequent reswelling of the collapsed film is only observed in the case of having applied a thermal stimulus of 20 to 40 °C. The normalized film thickness and the D2O amount of each layer in the PMEO2MA-b-POEGMA300 films are consistent at the end of the two different thermal stimuli. Hence, it can be concluded that the thermal history does not influence the final state of the PMEO2MA-b-POEGMA300 films upon heating. Based on this property, these thin films are especially suitable for the temperature switches on the nanoscale, which may experience different thermal histories.

We report the formation mechanism and compositions of a solid-electrolyte interphase (SEI) on a microporous carbon/sulfur (MC/S) cathode in Li–S batteries using a carbonate-based electrolyte (1 M L...

While sodium ion (Na+) itself cannot intercalate into graphitic structure to form binary graphite-intercalation-compounds (GICs) as its alkaline brothers (lithium, potassium etc.) do, the intercalation of its solvated form [Na(solvent)x]+ can readily happen, leading to reversible formation of ternary GICs at stage 1, as long as used solvent molecules are stable against reduction, such as ethers. However, a mystery still remains: what causes the initial irreversible capacity loss given that co-intercalation requires an interphase-free surface? In this work, we answered this fundamental question by elaborately examining the solvation structures, desolvation process and the corresponding electrochemical reduction stability of ether-based solvated Na+. Based on the understanding, a simple and effective approach was proposed to significantly increase the initial coulombic efficiency of sodium-ether co-intercalation. Such precise control over solvation-sheath and interfacial structures provides molecular-level guidance to the designing of new electrolyte systems and graphite-intercalation chemistries.

A water-in-salt electrolyte (WiSE) offers an electrochemical stability window much wider than typical aqueous electrolytes but still falls short in accommodating high-energy anode materials, mainly...

In this work, we demonstrate that intrinsically altering the reaction pathway of a sulfur-based cathode with designed additional redox activities could simultaneously suppress polysulfide shuttling...

The solid–electrolyte interphase (SEI) dictates the performance of most batteries, but the understanding of its chemistry and structure is limited by the lack of in situ experimental tools. In this work, we present a dynamic picture of the SEI formation in lithium-ion batteries using in operando liquid secondary ion mass spectrometry in combination with molecular dynamics simulations. We find that before any interphasial chemistry occurs (during the initial charging), an electric double layer forms at the electrode/electrolyte interface due to the self-assembly of solvent molecules. The formation of the double layer is directed by Li+ and the electrode surface potential. The structure of this double layer predicts the eventual interphasial chemistry; in particular, the negatively charged electrode surface repels salt anions from the inner layer and results in an inner SEI that is thin, dense and inorganic in nature. It is this dense layer that is responsible for conducting Li+ and insulating electrons, the main functions of the SEI. An electrolyte-permeable and organic-rich outer layer appears after the formation of the inner layer. In the presence of a highly concentrated, fluoride-rich electrolyte, the inner SEI layer has an elevated concentration of LiF due to the presence of anions in the double layer. These real-time nanoscale observations will be helpful in engineering better interphases for future batteries. An operando mass spectrometry technique, along with molecular dynamics simulations, unveils the evolution of the solid–electrolyte interphase chemistry and structure in lithium-ion batteries during the first cycle.

The linear shrinkage behavior in thermoresponsive diblock copolymer films and its potential application in temperature sensors are investigated. The copolymer is composed of two thermoresponsive blocks with different transition temperatures (TTs): di(ethylene glycol) methyl ether methacrylate (MEO2MA; TT1 = 25 °C) and poly(ethylene glycol) methyl ether methacrylate (OEGMA300; TT2 = 60 °C) with a molar ratio of 1:1. Aqueous solutions of PMEO2MA-b-POEGMA300 show a three-stage transition upon heating as seen with optical transmittance and small-angle X-ray scattering: dissolution (T TT2). Due to the restrictions in the polymer chain arrangement introduced by the solid Si substrate, spin-coated PMEO2MA-b-POEGMA300 films exhibit an entirely different internal structure and transition behavior. Neutron reflectivity shows the absence of an ordered structure normal to the Si substrate in as-prepared PMEO2MA-b-POEGMA300 films. After exposure to D2O vapor for 3 h and then increasing the temperature above its TT1 and TT2, the ordered structure is still not observed. Only a D2O enrichment layer is formed close to the hydrophilic Si substrate. Such PMEO2MA-b-POEGMA300 films show a linear shrinkage between TT1 and TT2 in a D2O vapor atmosphere. This special behavior can be attributed to the synergistic effect between the restrained collapse of the PMEO2MA blocks by the still swollen POEGMA300 blocks and the impedance of chain arrangement by the Si substrate. Based on this unique behavior, spin-coated PMEO2MA-b-POEGMA300 films are further prepared into a temperature sensor by implementing Ag electrodes. Its resistance decreases linearly with temperature between TT1 and TT2.

Lithium metal anodes have attracted extensive attention owing to their high theoretical specific capacity. However, the notorious reactivity of lithium prevents their practical applications, as evidenced by the undesired lithium dendrite growth and unstable solid electrolyte interphase formation. Here, we develop a facile, cost-effective and one-step approach to create an artificial lithium metal/electrolyte interphase by treating the lithium anode with a tin-containing electrolyte. As a result, an artificial solid electrolyte interphase composed of lithium fluoride, tin, and the tin-lithium alloy is formed, which not only ensures fast lithium-ion diffusion and suppresses lithium dendrite growth but also brings a synergistic effect of storing lithium via a reversible tin-lithium alloy formation and enabling lithium plating underneath it. With such an artificial solid electrolyte interphase, lithium symmetrical cells show outstanding plating/stripping cycles, and the full cell exhibits remarkably better cycling stability and capacity retention as well as capacity utilization at high rates compared to bare lithium., Here the authors report a simple method to create a solid electrolyte interphase that is tightly anchored onto the surface of lithium metal anode. This artificial structure suppresses dead and dendrite Li and stores Li via formation of alloys, enabling impressive battery performance.

A novel technique is demonstrated for the fabrication of silicon nanopillar arrays with high aspect ratios. Our technique leverages on an “antenna effect” present on a chromium (Cr) hard mask during ion-coupled plasma (ICP) etching. Randomly distributed sharp tips around the Cr edge act as antennas that attract etchant ions, which in turn enhance the etching of the Cr edge. This antenna effect leads to a smaller Cr mask size and thus a smaller nanopillar diameter. With optimized SF6 and CHF3 gas flow during ICP etching, we could achieve nanopillar arrays with sub-30 nm diameter, over 20 aspect ratio, and steep sidewall without collapse. The proposed technique may help break the limit of traditional nanopillar array fabrication, and be applied in many areas, such as Surface-Enhanced Raman Scattering (SERS). A series of SERS simulations performed on nanopillar arrays fabricated by this technique show an obvious Raman spectrum intensity enhancement. This enhancement becomes more obvious when the diameter of the nanopillar becomes smaller and the aspect ratio becomes higher, which may be explained by a high light absorption, the lightning-rod effect, and a greater number of free electrons available at the surface due to the higher density of the surface state.

Summary As a legacy left behind by classical analytical electrochemistry in pursuit of ideal electrodics, and classical physical electrochemistry in pursuit of the most conductive ionics, the study of non-aqueous electrolytes has been historically confined within a narrow concentration regime around 1 molarity (M). This confinement was breached in recent years when unusual properties were found to arise from the excessive salt presence, which often bring benefits to electrochemical, thermal, transport, interfacial, and interphasial properties that are of significant interest to the electrochemical energy storage community. This article provides an overview on this newly discovered and under-explored realm, with emphasis placed on their applications in rechargeable batteries.

Carbonate-based electrolytes have been extensively employed in commercial Li-ion batteries, but they face numerous interphasial stability challenges while supporting the high-voltage cathode chemistries and lithium metal anode, which result in electrolyte decomposition, electrode polarization, lithium dendritic growth and transition metal dissolution during cycling. Herein, a novel trifunctional electrolyte additive, trimethoxy(3,3,3-trifluoropropyl)silane (TTS), is proposed to address these challenges simultaneously. Through preferential reduction and oxidation, TTS constructs high stability protective films on both lithium metal anode and high voltage cathode surfaces, which effectively improves the interphasial stability of the electrode/electrolyte. In addition, the Si and O elements show great capability of capturing and eliminating the detrimental HF in the electrolyte. The capacity retention of lithium metal batteries constructed with a 5 V-class cathode LiNi0.5Mn1.5O4/Li reaches 92% after 500 cycles in the presence of only 2% TTS, which is 44% higher than that of the reference without the additive.

Water cut crude oil needs to be deeply dehydrated before further transportation or refining because water residuals not only tremendously increase the transportation cost and energy consumption, but also harm the oil delivery pipelines and refining equipment. Herein, we report carboxylated wood-based sponges (CWS) with underoil super-hydrophilicity for removing water residuals from crude oil. These CWS are made of aligned cellulose nanofibers after the removal of lignin and hemicellulose from natural balsa wood. Removing lignin and hemicellulose breaks the thin cell walls of balsa wood, resulting in a lamellar structure in the freeze-dried CWS. This lamellar architecture endows the CWS with high mechanical compressibility and good elastic recovery. The CWS show fast and effective dehydration for crude oil with water residuals as low as 20 ppm. The absorbed crude oil can be easily recovered from the CWS by simple squeezing. Additionally, the CWS are not only reusable without performance decline during long-term operation, but also show good chemical stability even in strong acidic and basic environments. These results indicate that the CWS have great potential for deep dehydration of crude oil, especially for water-in-crude oil emulsions.

In the present work, polydopamine nanotubes (PDA NTs) decorated with silver (Ag) nanoparticles (NPs) were successfully fabricated via a template induced self-polymerization of dopamine, followed by...

Performances of lithium-ion batteries at subambient temperatures are extremely restricted by the resistive interphases originated from electrolyte decomposition, especially on the anode surface. This work reports a novel strategy that an anode interphase of low impedance is constructed by applying an electrolyte additive dimethyl sulfite (DMS). Electrochemical measurements indicate that the as-constructed interphase provides graphite/LiNi0.5Co0.2Mn0.3O2 pouch cells with excellent low-temperature performance, outperforming the interphase constructed by 1,3,2-dioxathiolane 2,2-dioxide (DTD), a common commercially used electrolyte additive. Spectral characterizations in combination with theoretical calculations demonstrate that the improved performance is attributed to the unique molecular structure of DMS, which presents appropriate reduction activity and constructs the more stable and ionically conductive anode interphase due to the weaker combination of its reduction product with lithium ions than DTD. This rational design of interphases via an additive structure has been proven to be a low cost but rather an effective approach to tailor the performances of lithium-ion batteries.

It is extremely challenging to reclaim materials from spent lithium ion batteries that have more complicated chemistries than lead-acid batteries. In this work, a new approach is proposed to reclaim the graphitic anode materials from spent lithium ion batteries in electric vehicles, which involves a facile water treatment. With compositional and structural characterizations, it is found that the spent graphite anode still retains integrated graphitic structure with an inclusion of electrolyte decomposition products that are mainly responsible for the failure of a battery. Water treatment removes most of these impurities, opens Li+ transport channel and restores the graphite to be electrochemically active. After 100 cycles, the reclaimed graphite retains a capacity of 345 mAh g−1, which is comparable to the 347 mAh g−1 for commercial graphite. The approach we proposed requires neither harmful chemicals nor high temperature operation, providing a green and viable solution to the ever increasing threat caused by the vast mass of spent lithium ion batteries generated by electric vehicle industry.

Although electrolyte additives have been extensively used in modern Li-ion batteries, the practice remained a “dark-art” with little rationale understanding. In this work, using two representative additives that have been extensively for superior electrochemical performances, i.e., vinylene carbonate (VC) and LiPO2F2 (LPF), we thoroughly investigated the fundamental chemistry and electrochemistry involved in Li-ion battery environment and explored the underneath mechanism. The analyses performed on bulk electrolyte and surfaces of both graphitic anode and transition metal oxide cathode reveal complicated reaction cascades among these additives with electrolyte components as well as electrode materials. It was found that the effectiveness of these additives lies not only in how they participate the interphasial chemistries, but also in how they suppress the major side reactions between the bulk electrolyte solvents, the trans-esterification. The correlation between the additive chemistries and electrochemical performances provide valuable guidelines to rational selection, design and synthesis of future additives of higher effectiveness and for new battery chemistries.

Owing to unique structures and properties, 2D layered materials have exhibited great potentials for energy-related applications. Among these, 2D Bi-based layered materials which possess intriguing characteristics for energy conversion and storage systems have attracted tremendous attention. In this review, the structural and electronic properties of 2D Bi-based layered materials classified into four categories (unitary, binary, ternary and multinary) are introduced. Their promising applications in energy conversion and storage are reviewed in details, with particular emphasis on photocatalysis, electrocatalysis, solar cells, thermoelectrics, optoelectronics and rechargeable batteries. Finally, based on current research progress, future perspectives for exploring and developing advanced 2D Bi-based layered energy conversion and storage materials are presented.

The use of 'water-in-salt' electrolytes has considerably expanded the electrochemical window of aqueous lithium-ion batteries to 3 to 4 volts, making it possible to couple high-voltage cathodes with low-potential graphite anodes1-4. However, the limited lithium intercalation capacities (less than 200 milliampere-hours per gram) of typical transition-metal-oxide cathodes5,6 preclude higher energy densities. Partial7,8 or exclusive9 anionic redox reactions may achieve higher capacity, but at the expense of reversibility. Here we report a halogen conversion-intercalation chemistry in graphite that produces composite electrodes with a capacity of 243 milliampere-hours per gram (for the total weight of the electrode) at an average potential of 4.2 volts versus Li/Li+. Experimental characterization and modelling attribute this high specific capacity to a densely packed stage-I graphite intercalation compound, C3.5[Br0.5Cl0.5], which can form reversibly in water-in-bisalt electrolyte. By coupling this cathode with a passivated graphite anode, we create a 4-volt-class aqueous Li-ion full cell with an energy density of 460 watt-hours per kilogram of total composite electrode and about 100 per cent Coulombic efficiency. This anion conversion-intercalation mechanism combines the high energy densities of the conversion reactions, the excellent reversibility of the intercalation mechanism and the improved safety of aqueous batteries.

Carbon-coated SiO is the most promising alternative to the graphite anode for improving the energy density of currently commercialized lithium-ion batteries but exhibits poor cyclic stability that leaves an unclear mechanism. To address this issue, the surface properties of commercial carbon-coated silicon monoxide are investigated in a 1.0 M LiPF6-dimethyl carbonate electrolyte with and without ethylene carbonate (EC), with a comparison of graphite. Unlike graphite that can work well in the electrolytes with and without EC during initial 30 cycles, carbon-coated SiO suffers a serious capacity decay, especially in the electrolyte without EC. By identifying the samples after various cycles, it is found that a relatively stable interphase that makes graphite work well cannot be built on carbon-coated SiO. The chemical analyses demonstrate that there is a strong interaction between SiO with hydrofluoric acid in the electrolyte, which leads to destruction of the carbon-coating layer and prevents the formation of a protective interphase.

The energy density of commercial Li-ion batteries (LIBs) using LiCoO2 is adversely affected by the limited access to the Li stored in the CoO2 lattice, which is imposed partially by the instability of carbonate-based electrolytes at potentials higher than 4.5 V. In this work, we report a novel approach to fully utilize these extra Li via simultaneously stabilizing anode and cathode interfaces with a designed additive, 4-propyl-[1,3,2]dioxathiolane-2,2-dioxide (PDTD), which strongly coordinates with Co ions dissolved in electrolytes while decomposing to form protective interphases on both cathode and anode surfaces. The Co ions present in the electrolyte deposit on the anode in the form of a coordination complex with PDTD, avoiding the formation of Co metal that will catalyze the reduction decomposition of the additive-free electrolyte. The presence of PDTD in the electrolyte enables a higher charging potential of 4.45 V for LiCoO2/graphite cells, which significantly improves the energy density and cycling stability of this cathode chemistry that has already been used extensively in commercial LIBs.

The mussel-inspired catechol-based strategy has been well recognized as a promising alternative to design and exploit new generation adhesive materials applicable in many fields, ranging from biomedical adhesives to coatings of biomedical devices and engineering applications. However, in situ achievement of tough adhesion capability to substrate surfaces (e.g., minerals) is severely limited under the physiological environment or seawater condition (namely, relatively high salinity and mild alkalinity). In this work, a facile and versatile approach is proposed to in situ achieve robust wet adhesion in aqueous solutions of high salinity and mild alkalinity, via integrating primary amines into mussel-inspired polydopamine (PDA). By using a surface forces apparatus (SFA), the corresponding interaction behaviors have been systematically investigated. The strong wet adhesion was demonstrated and achieved via a synergetic effect of amine and PDA to the wet surfaces, including the surface salt displacement assisted by primary amine, strong adhesion to substrates facilitated by the catechol groups on PDA moieties, and enhanced cohesion through their cation-π interactions. Our results provide useful insights into the design and development of high-performance underwater adhesives and water-resistance materials.

The effective removing water from water-in-oil emulsions is of great importance in fuel oil production and waste oil recovery. Ceramic membranes with excellent mechanical, and chemical stability have been increasingly used in the treatment of water-in-oil emulsions. However, membrane fouling is still a challenge needed to be solved due to the intrinsic hydrophilic property of these ceramic membranes. Herein, mussel-inspired and nanostructured coatings have been fabricated to modify the ceramic membrane with superhydrophobic/oleophilic surfaces. First, polydopamine (PDA) is deposited on the ceramic membrane surface using CuSO4/H2O2 as a trigger. Then, the formed PDA coating acts as a platform to induce the metallization of Ag ions into Ag nanoparticles. Subsequently hexadecanethiol (HDT) is grafted on the obtained membranes. The membrane morphologies, chemistry and wettability after each step of surface modification are characterized. CuSO4/H2O2 accelerates the deposition process of PDA on ceramic membrane surface with much more uniformity. Hierarchical nanostructure by silver nanoparticles is formed on PDA coated membranes. And the synergistic effect of surface hierarchical structure and HDT modification leads to the membrane surface's superhydrophobicity in air and a non-adhesive behavior to the water droplet under oil. The final modified membranes also show good stability in a series of solvents, and show excellent antifouling property in the filtration of water-in-oil emulsions. This modification method provides a facile and efficient strategy for preparing durable antifouling ceramic membranes for the treatment of organic solvents.

Deposition of dopamine and tannic acid has received great attention in the fields of surface and interface science and technology. The deposition behaviors of various metal–phenolic systems have been investigated, and it is generally accepted that at least one catechol group is essential to the formation of the coatings. Herein, we report a novel and effective surface-coating system based on the coordination complexes of FeIII ions with a natural product juglone that contains only one phenolic hydroxyl. We investigated the deposition behaviors of this novel system on various substrates. Microporous polypropylene membrane modified with juglone/FeIII coatings is superhydrophilic and underwater superoleophobic, showing high separation efficiency and good reusability for various oil/water emulsions. In addition, the modified membrane can adsorb anionic dyes and selectively remove them from dye mixtures with high efficiency. We further demonstrated that the coating is a result of the synergetic effect of juglo...

While the solid-electrolyte-interphase (SEI) originating from carbonate-based electrolytes has been extensively studied due to the success of Li-ion batteries, significantly less is known about the SEI formed in ether-based electrolytes, which have become increasingly important for many “beyond-Li ion” batteries, including lithium-sulfur and other lithium metal battery systems. Li dendrite growth and poor cycling efficiencies related to high rate and/or high capacity cycling of lithium are two of the primary factors limiting practical application of Li metal anodes. Similar to graphite in Li-ion batteries, these behaviors are inextricably linked to the mechanism for SEI formation, the resulting interphase chemistry, and the film stability during cycling—all of which require further understanding. Employing both computational and experimental means in this effort, we investigated the reduction chemistry of dimethoxyethane (DME) and 1,3-dioxolane (DOL) on the surface of metallic lithium. We determined that ether-based SEIs are layer-structured, with an outer organic/polymeric layer consisting of lithium oligoethoxides with C-C-O or O-C-O linkages and an inner layer of simple inorganic oxides (Li2O). Remarkably, although Li+ is preferentially solvated by DME, it is the cyclic DOL that primarily contributes to the interphase chemistry. This selective electrochemical reduction of ether solvents is corroborated by precise calculation of transition state structures and energies, providing a valuable guide for future design and manipulation of Li anode interphasial chemistries.

Electrolyte additives have been extensively used as an economical approach to improve Li-ion battery (LIB) performances; however, their selection has been conducted on an Edisonian trial-and-error basis, with little knowledge about the relationship between their molecular structure and reactivity as well as the electrochemical performance. In this work, a series of phosphate additives with systematic structural variation were introduced with the purpose of revealing the significance of additive structure in building a robust interphase and electrochemical property in LIBs. By comparing the interphases formed by tripropyl phosphate (TPPC1), triallyl phosphate (TPPC2), and tripropargyl phosphate (TPPC3) containing alkane, alkene, and alkyne functionalities, respectively, theoretical calculations and comprehensive characterizations reveal that TPPC3 and TPPC2 exhibit more reactivity than TPPC1, and both can preferentially decompose both reductively and oxidatively, forming dense and protective interphases on both the cathode and anode, but they lead to different long-term cycling behaviors at 55 °C. We herein correlate the electrochemical performance of the high energy Li-ion cells to the molecular structure of these additives, and it is found that the effectiveness of TPPC1, TPPC2, and TPPC3 in preventing gas generation, suppressing interfacial resistance growth, and improving cycling stability can be described as TPPC3 > TPPC2 > TPPC1, i.e., the most unsaturated additive TPPC3 is the most effective additive among them. The established correlation between structure-reactivity and interphase-performance will doubtlessly construct the principle foundation for the rational design of new electrolyte components for future battery chemistry.

The deepening crisis of freshwater resources has been driving the further development of new types of membrane-based desalination technologies represented by nanofiltration membranes. Solving the existing trade-off limitation on enhancing the water permeance and the rejection of salts is currently one of the most concerned research interests. Here, a facile and scalable approach is proposed to tune the interfacial polymerization by constructing a calcium alginate hydrogel layer on the porous substrates. The evenly coated thin hydrogel layer can not only store amine monomers like the aqueous phase but also suppress the diffusion of amine monomers inside, as well as provide a flat and stable interface to implement the interfacial polymerization. The resultant polyamide nanofilms have a relatively smooth morphology, negatively charged surface, and reduced thickness which facilitate a fast water permeation while maintaining rejection efficiency. As a result, the as-prepared composite membranes show improved water permeance (~30 Lm−2h−1bar−1) and comparable rejection of Na2SO4 (&gt, 97%) in practical applications. It is proved to be a feasible approach to manufacturing high-performance nanofiltration membranes with the assist of alginate hydrogel regulating interfacial polymerization.

The introduction of “water‐in‐salt” electrolyte (WiSE) concept opens a new horizon to aqueous electrochemistry that is benefited from the formation of a solid‐electrolyte interphase (SEI). However, such SEI still faces multiple challenges, including dissolution, mechanical damaging, and incessant reforming, which result in poor cycling stability. Here, we report a polymeric additive, polyacrylamide (PAM) that effectively stabilizes the interphase in WiSE. With the addition of 5 molar % PAM to 21 mol kg−1 LiTFSI electrolyte, a LiMn2O4∥L‐TiO2 full cell exhibits enhanced cycling stability with 86 % capacity retention after 100 cycles at 1 C. The formation mechanism and evolution of PAM‐assisted SEI was investigated using operando small angle neutron scattering and density functional theory (DFT) calculations, which reveal that PAM minimizes the presence of free water molecules at the anode/electrolyte interface, accelerates the TFSI− anion decomposition, and densifies the SEI., Polyacrylamide (PAM) was introduced to “water‐in‐salt” electrolyte (21 mol kg−1 LiTFSI) to realize the formation of an effective solid‐electrolyte interphase (SEI) in LiMn2O4∥L‐TiO2 full cells by lowering the cathodic limit in the electrochemical stability window (ESW) and suppressing the hydrogen evolution.

Cryogenic transmission electron microscopy (cryo-TEM) is a valuable tool recently proposed to investigate battery electrodes. Despite being employed for Li-based battery materials, cryo-TEM measurements for Na-based electrochemical energy storage systems are not commonly reported. In particular, elucidating the chemical and morphological behavior of the Na-metal electrode in contact with a non-aqueous liquid electrolyte solution could provide useful insights that may lead to a better understanding of metal cells during operation. Here, using cryo-TEM, we investigate the effect of fluoroethylene carbonate (FEC) additive on the solid electrolyte interphase (SEI) structure of a Na-metal electrode. Without FEC, the NaPF6-containing carbonate-based electrolyte reacts with the metal electrode to produce an unstable SEI, rich in Na2CO3 and Na3PO4, which constantly consumes the sodium reservoir of the cell during cycling. When FEC is used, the Na-metal electrode forms a multilayer SEI structure comprising an outer NaF-rich amorphous phase and an inner Na3PO4 phase. This layered structure stabilizes the SEI and prevents further reactions between the electrolyte and the Na metal., The solid electrolyte interphase (SEI) strongly affects the cycling behaviour of rechargeable alkali metal cells. Here, the authors investigate via cryo-electron microscopy the SEI formed on a Na metal electrode using fluoroethylene carbonate-containing electrolyte.

Modified metal–organic frameworks (MOFs) doping with enzymes exhibit high enzyme stability and catalytic performance, which is a research hotspot in the field of enzyme-based sensing. Although the MOF-enzyme constitutes a 3D structure in the nanoscale, the macroscopic assembly configuration still stays in 1D or 2D structures, limiting sensing applications towards complex biological targets. Herein, the MOF-enzyme hybrid nanosystem was assembled into 3D porous conductive supports via a controllable physical embedding method, displaying high enzymatic loading, stability and cascade catalytic performance. The modified MOFs combing with enzymes served as a sensing reaction system, and the conductive hollow fiber membranes (HFMs) served as a functional platform. The multifunctional device integrates pumpless hydrodynamic transport, interconnected conductive polymer, and blood separation modules, showing fast capillary fluid flow, trace sampling (3 μL), high selectivity and accuracy. The linear sensing range was in 2–24 mM glucose, 0.05–6 mM lactic acid, and 0.1–10 mM cholesterol, respectively, with sensitivities of 24.2, 150, 73.6 nA mM−1. Furthermore, this strategy of modular assembly of biosensing array can easily implement multiplex metabolites detection simultaneously.

Organic solvent nanofiltration (OSN) is regarded as a promising separation technology in chemical and pharmaceutical industries. However, it remains a great challenge in fabricating OSN membranes with high permeability and precise selectivity by simple, transfer-free, and up-scalable processes. Herein, we report lysozyme nanofilm composite membranes (LNCM) prepared by one-step methods with hydrophobic substrates at the air/water interface. The microporous substrates not only promote the heterogeneous nucleation of amyloid-like lysozyme oligomers to construct small pores in the formed nanofilms but also benefit for the simultaneous composition of LNCM via hydrophobic interactions. The constructed nanopores are reduced to around 1.0 nm, and they are demonstrated by grazing incidence small-angle X-ray scattering with a closely packed model. The LNCM can tolerate most organic polar solvents and the permeability surpasses most of state-of-the-art OSN membranes.

Mussel-inspired poly(catecholamine) coatings from polydopamine (PDA) have been widely studied to design functional coatings for various materials. The chemical precursor of dopamine (DA), levodopa (l-DOPA, 3,4-dihydroxyphenyl-l-alanine), is known as the main element of mussel adhesive foot protein, but it is relatively hard to be constructed into a desirable coating on a given material surface under the same conditions as those for DA. Herein, we report a codeposition strategy to achieve the rapid fabrication of mussel-inspired coatings by l-DOPAwith polyethyleneimine (PEI) and to deeply understand the formation mechanism of those aggregates and coatings from l-DOPA/PEI. DFT calculations, fluorescence spectra, nuclear magnetic resonance analysis, and liquid chromatography-tandem mass spectrometry identification demonstrate that the formation of l-DOPA/PEI aggregates is effectively accelerated by PEI crosslinking with those intermediates of oxidized l-DOPA, including l-DOPAquinone and 5,6-dihydroxyindole-2-carboxylic acid as well as 5,6-dihydroxyindole, through Michael-addition and Schiff-base reactions. Therefore, we can facilely control the growth rate and the particle size of the l-DOPA/PEI aggregates in the deposition solution by adjusting the concentration of PEI. The coating formation rate of l-DOPA/PEI is four times faster than that of PDA and DA/PEI within 12 h. These l-DOPA/PEI coatings are demonstrated to display potential as structure colors, superhydrophilic surfaces, and antibacterial materials.

"Water-in-salt" (WIS) and "water-in-bisalt" (WIBS) electrolytes have recently been developed for Li-ion batteries, combining the safety and environmental friendliness of aqueous electrolytes with a larger operating window made possible by a solid-electrolyte interphase. We report quasielastic neutron scattering (QENS) measurements on solutions of a WIS electrolyte at two concentrations, 13.9 and 21 m (molal) lithium bis(trifluoromethane)sulfonimide LiTFSI in H2O/D2O and a WIBS electrolyte at (21 m LiTFSI + 7 m lithium triflate (LiOTf)) in H2O/D2O. The data were Fourier transformed to obtain experimental intermediate scattering functions (ISFs) and compared with corresponding quantities obtained from molecular dynamics (MD) simulations. Both QENS and MD ISFs could be fitted well by a single stretched exponential function to obtain apparent translational diffusion coefficients for the water molecules. The QENS values agree well with the MD simulations for the 13.9 and 21 m solutions, but MD simulations predict a slower relaxation of water compared to QENS for the WIBS electrolyte. Comparison of the incoherent and coherent scattering reveals much faster water dynamics compared with structural relaxation of the ionic framework, consistent with the nanodomain picture where the lithium diffusion occurs through the tortuous water domain around the slower relaxing ionic matrix, leading to highly non-Gaussian water motion.

Mechanism of targeted microwave energy transfer drives solid-liquid intercalation to completion in minutes., In chemical reactions, the breaking and formation of chemical bonds usually need external energy to overcome the activation barriers. Conventional energy delivery transfers energy from heating sources via various media, hence losing efficiency and inducing side reactions. In contrast, microwave (MW) heating is known to be highly energy efficient through dipole interaction with polar media, but how exactly it transmits energy to initiate chemical reactions has been unknown. Here, we report a rigorous determination of energy delivery mechanisms underlying MW-enabled rapid hydrothermal synthesis, by monitoring the structure and temperature of all the involved components as solid-liquid intercalation reaction occurs using in situ synchrotron techniques. We reveal a hitherto unknown direct energy transmission between MW irradiation source and the targeted reactants, leading to greatly reduced energy waste, and so the ultrafast kinetics at low temperature. These findings open up new horizons for designing material synthesis reactions of high efficiency and precision.

By virtue of the layered structure, van der Waals (vdW) magnets are sensitive to the lattice deformation controlled by the external strain, providing an ideal platform to explore the one-step magnetization reversal that is still conceptual in conventional magnets due to the limited strain-tuning range of the coercive field. In this study, a uniaxial tensile strain is applied to thin flakes of the vdW magnet Fe3 GeTe2 (FGT), and a dramatic increase of the coercive field (Hc ) by more than 150% with an applied strain of 0.32% is observed. Moreover, the change of the transition temperatures between the different magnetic phases under strain is investigated, and the phase diagram of FGT in the strain-temperature plane is obtained. Comparing the phase diagram with theoretical results, the strain-tunable magnetism is attributed to the sensitive change of magnetic anisotropy energy. Remarkably, strain allows an ultrasensitive magnetization reversal to be achieved, which may promote the development of novel straintronic device applications.

A stable solid electrolyte interphase (SEI) has been proven to be a key enabler to most advanced battery chemistries, where the reactivity between the electrolyte and the anode operating beyond the electrolyte stability limits must be kinetically suppressed by such SEIs. The graphite anode used in state-of-the-art Li-ion batteries presents the most representative SEI example. Because of similar operation potentials between graphite and silicon (Si), a similar passivation mechanism has been thought to apply on the Si anode when using the same carbonate-based electrolytes. In this work, we found that the chemical formation process of a proto-SEI on Si is closely entangled with incessant SEI decomposition, detachment, and reparation, which lead to continuous lithium consumption. Using a special galvanostatic protocol designed to observe the SEI formation prior to Si lithiation, we were able to deconvolute the electrochemical formation of such dynamic SEI from the morphology and mechanical complexities of Si and showed that a pristine Si anode could not be fully passivated in carbonate-based electrolytes.

Lithium metal is viewed as the ultimate battery anode because of its high theoretical capacity and low electrode potential, but its implementation has been limited by low Coulombic efficiency and dendrite formation above a critical current density. Determining the fundamental properties dictating lithium metal plating–stripping behavior is challenging because characterization techniques are limited by the sensitivity of lithium metal to damage by external probes, which regularly results in altered morphology and chemistry. Motivated by recent application of cryogenic transmission electron microscopy (cryo-TEM) to characterize lithium metal at the atomic scale, we explore the cryogenic focused ion beam (cryo-FIB) method as a quantitative tool for characterizing the bulk morphology of electrochemically deposited lithium and as a technique that enables TEM observation of Li-metal/solid-state electrolyte interfaces. This work highlights the importance of cryo-FIB methodology for preparing sensitive battery ma...